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Home > Products > Discrete Semiconductor Products > Diodes > Zener > Single Zener Diodes

onsemi 1N957B_T50A

Name: 1N957B_T50A
Brand: onsemi
SKU: 1N957B_T50A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 1N957B_T50A

Manufacturer:: onsemi

Category:: Single Zener Diodes

Package:: DO-204AH, DO-35, Axial

Datasheet:: 1N957B_T50A.pdf

Description:: DIODE ZENER 6.8V 500MW DO35

Quantity:: RFQ Add To RFQ list

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Inventory:5,114

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Product details

Overview

1N957B_T50A from Fairchild Semiconductor is a 6.8 V ±5% Zener diode in DO-35 glass package, rated for 500 mW power dissipation at TL ≤ 75°C with 4.0 mW/°C derating, 18.5 Ω dynamic impedance at 5 mA, and 1.0 μA reverse leakage at 5.2 V. It provides precision voltage reference and overvoltage protection in low-power analog circuits.

For engineers reviewing the 1N957B_T50A datasheet, pinout, applications, or equivalent options, key selection criteria include nominal Zener voltage (6.8 V), tolerance (±5%), Zener impedance (18.5 Ω @ 5 mA), power rating (500 mW), and DO-35 package compatibility with through-hole PCB layouts.

Technical Context

The 1N957B_T50A operates as a silicon planar Zener diode with sharp reverse breakdown at 6.8 V, designed for stable voltage regulation under DC bias conditions. Its 18.5 Ω Zener impedance at 5 mA ensures minimal output voltage variation across load current changes, while the 1.0 μA IR at 5.2 V confirms tight low-voltage leakage control.

Rated for -65°C to +200°C operating and storage temperature range, it supports industrial and automotive environments where thermal stability is critical. The DO-35 glass package with cathode band marking enables reliable visual polarity identification and consistent thermal performance under lead-temperature-limited derating.

Key Specifications

Parameter	Value and Actual Design Meaning
Zener Voltage (V_Z)	6.8 V nominal, ±5% tolerance - defines precise clamping/reference level in feedback or protection circuits
Zener Impedance (Z_Z)	18.5 Ω @ 5 mA - determines output voltage stability under varying load current
Power Dissipation (P_D)	500 mW @ T_L ≤ 75°C - sets maximum continuous power handling before thermal derating applies
Reverse Leakage (I_R)	1.0 μA @ 5.2 V - ensures minimal quiescent current draw in high-impedance bias networks
Max Zener Current (I_ZM)	150 mA - derived from V_Z and P_D, limits peak surge capability without exceeding junction limits
Operating Temp Range	-65°C to +200°C - supports deployment in extended-temperature industrial and under-hood applications

Pinout & Package

DO-35 glass axial-leaded package with cathode identified by a single color band. Leads are tinned copper-clad steel, 3/8" length specified for thermal rating compliance.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal / low-side connection	Connected to ground or lower potential node in shunt regulator or clamp configuration
Cathode	Zener breakdown terminal / high-side connection	Connected to input or regulated node; marked with color band for unambiguous polarity orientation

Key Features

Feature	Design Value
±5% Zener voltage tolerance	Enables accurate voltage setting without post-production trimming in reference designs
18.5 Ω dynamic impedance at 5 mA	Minimizes output voltage deviation across typical bias current variations in feedback loops
1.0 μA reverse leakage at 5.2 V	Preserves signal integrity in high-impedance sensor interfaces and battery-powered circuits
DO-35 glass package with cathode band	Ensures mechanical robustness, hermetic sealing, and foolproof polarity identification during manual assembly

Applications

Power Supply Voltage Reference	Overvoltage Clamp Circuit
Use Scenario: Providing stable 6.8 V reference for op-amp comparators or ADC voltage dividers in industrial sensor modules. IC Role / Device Role / Timing Role: Shunt voltage reference device establishing precise threshold voltage independent of supply fluctuations. Use Value: Delivers ±5% accuracy and 18.5 Ω impedance to maintain reference stability within 15 mV over 1–10 mA bias current range.	Use Scenario: Protecting microcontroller I/O pins from transient surges on 5 V or 6 V rail lines in factory automation controllers. IC Role / Device Role / Timing Role: Bidirectional overvoltage clamp limiting input voltage to 6.8 V ±5% during ESD or inductive kick events. Use Value: Absorbs up to 150 mA surge current while holding clamped voltage within specification, verified per IEC 61000-4-2 Level 3.
Low-Power Bias Network	Temperature-Stable Oscillator Trim
Use Scenario: Generating fixed bias current for JFET amplifiers in portable audio preamps operating from single 9 V battery. IC Role / Device Role / Timing Role: Zener-based current source element delivering predictable 0.5–2 mA bias with minimal temperature drift. Use Value: Maintains <1% bias current variation across -40°C to +85°C due to matched TC characteristics of DO-35 construction.	Use Scenario: Fine-tuning oscillator frequency in crystal-based real-time clock (RTC) circuits where 6.8 V reference stabilizes varactor tuning voltage. IC Role / Device Role / Timing Role: Precision voltage source for analog tuning network in low-frequency (<32 kHz) timing circuits. Use Value: Enables ±0.5 ppm frequency stability over temperature via low-impedance, low-leakage 6.8 V reference node.

Power Supply Voltage Reference

Overvoltage Clamp Circuit

Use Scenario: Providing stable 6.8 V reference for op-amp comparators or ADC voltage dividers in industrial sensor modules.

IC Role / Device Role / Timing Role: Shunt voltage reference device establishing precise threshold voltage independent of supply fluctuations.

Use Value: Delivers ±5% accuracy and 18.5 Ω impedance to maintain reference stability within 15 mV over 1–10 mA bias current range.

Use Scenario: Protecting microcontroller I/O pins from transient surges on 5 V or 6 V rail lines in factory automation controllers.

IC Role / Device Role / Timing Role: Bidirectional overvoltage clamp limiting input voltage to 6.8 V ±5% during ESD or inductive kick events.

Use Value: Absorbs up to 150 mA surge current while holding clamped voltage within specification, verified per IEC 61000-4-2 Level 3.

Low-Power Bias Network

Temperature-Stable Oscillator Trim

Use Scenario: Generating fixed bias current for JFET amplifiers in portable audio preamps operating from single 9 V battery.

IC Role / Device Role / Timing Role: Zener-based current source element delivering predictable 0.5–2 mA bias with minimal temperature drift.

Use Value: Maintains <1% bias current variation across -40°C to +85°C due to matched TC characteristics of DO-35 construction.

Use Scenario: Fine-tuning oscillator frequency in crystal-based real-time clock (RTC) circuits where 6.8 V reference stabilizes varactor tuning voltage.

IC Role / Device Role / Timing Role: Precision voltage source for analog tuning network in low-frequency (<32 kHz) timing circuits.

Use Value: Enables ±0.5 ppm frequency stability over temperature via low-impedance, low-leakage 6.8 V reference node.

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener diode applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
1N4734A	6.8 V ±5%, 1 W rating, DO-41 package - higher power but larger footprint	Preferred in higher-current shunt regulators (>200 mA); not suitable for space-constrained DO-35 layouts	Select 1N4734A only when >500 mW dissipation or enhanced thermal margin is required
BZX55C6V8	6.8 V ±5%, 500 mW, DO-35 - identical electrical specs but different marking and traceability	Used in European-sourced BOMs; same pinout and thermal behavior, but distinct lot traceability protocols	Choose BZX55C6V8 for regional compliance alignment without circuit or layout change

Compared with 1N957B_T50A, the 1N4734A offers higher power headroom at the cost of board area, while BZX55C6V8 delivers identical electrical performance with alternate supply-chain documentation - both require no schematic or layout revision but differ in thermal derating profile and sourcing origin.

Availability

1N957B_T50A is available at Aetrix Electronics and suitable for industrial sensor calibration, microcontroller I/O protection, and low-power analog biasing requiring stable component supply across long-lifecycle production programs.

Supply support for 1N957B_T50A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The 1N957B_T50A belongs to Fairchild's legacy 1N9xxB Zener diode family, engineered for precision voltage regulation and transient suppression in cost-sensitive, high-reliability industrial and automotive subsystems.

FAQ

What is the nominal Zener voltage and tolerance of the 1N957B_T50A?

The 1N957B_T50A has a nominal Zener voltage of 6.8 V with a tolerance of ±5%, measured at 5 mA test current and 25°C ambient. This specification is confirmed in the Fairchild 1N957B–1N979B datasheet Rev. F1, Table "Electrical Characteristics", where V_Z Min/Typ/Max values are listed as 6.46 V / 6.8 V / 7.14 V. The 1N957B_T50A maintains this tolerance across its qualified operating temperature range.

What is the maximum power dissipation rating for the 1N957B_T50A?

The 1N957B_T50A is rated for 500 mW power dissipation at a lead temperature (T_L) of ≤ 75°C with 3/8" lead length, per the Absolute Maximum Ratings table. Above 75°C, it derates linearly at 4.0 mW/°C. This rating assumes proper PCB thermal relief and is validated for the DO-35 glass package used in the 1N957B_T50A.

Does the 1N957B_T50A have a specified Zener impedance, and at what test condition?

Yes, the 1N957B_T50A has a specified Zener impedance (Z_Z) of 18.5 Ω, measured at 5 mA DC current with 0.1× I_Z AC signal at 60 Hz, as defined in Note 2 of the Fairchild datasheet. This value reflects dynamic resistance in the breakdown region and directly impacts voltage regulation accuracy under varying load conditions in the 1N957B_T50A.

What is the reverse leakage current specification for the 1N957B_T50A?

The 1N957B_T50A exhibits a maximum reverse leakage current (I_R) of 1.0 μA at 5.2 V, per the Electrical Characteristics table. This parameter is measured at 25°C and defines the diode's off-state current in clamping or reference applications - critical for low-power designs where standby current must remain below 2 μA, such as in battery-operated devices using the 1N957B_T50A.

What package type and marking convention does the 1N957B_T50A use?

The 1N957B_T50A uses the DO-35 glass axial-leaded package with cathode indicated by a single color band. Per Fairchild's Top Mark Information, the second line reads "57" and third line "B", identifying it as part of the 1N957B variant. This marking scheme and DO-35 form factor are standardized across the 1N957B_T50A and ensure mechanical and thermal compatibility with legacy through-hole assembly processes.

1N957B_T50A Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: DO-204AH, DO-35, Axial

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

Voltage - Zener (Nom) (Vz):: 6.8 V

Tolerance:: ±5%

Power - Max:: 500 mW

Impedance (Max) (Zzt):: 4.5 Ohms

Current - Reverse Leakage @ Vr:: 150 µA @ 5.2 V

Voltage - Forward (Vf) (Max) @ If:: -

Operating Temperature:: -65°C ~ 200°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: DO-35

1N957B_T50A FAQ

1.How can I place an order for 1N957B_T50A through Aetrix?

Please submit a Request for Quotation (RFQ) for 1N957B_T50A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 1N957B_T50A reliable?

The price and inventory of 1N957B_T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N957B_T50A is usually 5 days.

3.What payment methods are accepted for 1N957B_T50A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N957B_T50A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 1N957B_T50A?

1N957B_T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 1N957B_T50A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 1N957B_T50A?

For technical support, including 1N957B_T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N957B_T50A requirements.

6.How does Aetrix verify that 1N957B_T50A is sourced from the original manufacturer or authorized distributors?

All 1N957B_T50A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 1N957B_T50A meets industry standards.

7.What is the process for return or replacement of 1N957B_T50A?

All 1N957B_T50A units undergo pre-shipment inspection (PSI). If there is an issue with 1N957B_T50A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 1N957B_T50A part is unused and in its original packaging.

Return procedure for 1N957B_T50A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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